WDPN31 PGTW 091500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (PEIPAH) 
WARNING NR 27//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 05W (PEIPAH), LOCATED APPROXIMATELY 616 
NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTH-
NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED 
INFRARED SATELLITE IMAGERY SHOWS THE ASSOCIATED CONVECTION HAS 
SIGNIFICANTLY DEPLETED AS THE LOW LEVEL CIRCULATION CENTER (LLCC) 
HAS BECOME EVEN MORE NEBULOUS AND ILL-DEFINED. THE INITIAL POSITION 
IS BASED ON THE ABOVE ANIMATION AND EXTRAPOLATED FROM THE CURRENT 
STORM MOTION WITH POOR CONFIDENCE. THE INITIAL INTENSITY IS BASED ON 
THE DVORAK ESTIMATE FROM KNES AND REFLECTS THE WEAKENED STATE OF THE 
SYSTEM. UPPER-LEVEL ANALYSIS INDICATES TD 05W REMAINS IN A HARSH 
ENVIRONMENT WITH HIGH (20-25 KNOTS) EASTERLY VERTICAL WIND SHEAR 
(VWS). HOWEVER, A GOOD POLEWARD OUTFLOW IS PROVIDING VENTILATION TO 
THE REMNANT CONVECTION. THE CYCLONE IS IN A WEAK STEERING 
ENVIRONMENT AND IS TRACKING ERRATICALLY BUT SLOWLY NORTHWESTWARD 
TOWARD A BREAK IN THE SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TD PEIPAH WILL REMAIN IN THE WEAK STEERING ENVIRONMENT AS IT 
TRACKS SLOWLY NORTHWESTWARD TOWARDS THE WEAKNESS IN THE STR. AS THE 
HIGH VWS PERSISTS, THE SYSTEM IS EXPECTED TO STRUGGLE INTENSITY-WISE 
BEFORE MAKING LANDFALL INTO THE ISLAND OF SAMAR TOWARDS DISSIPATION. 
THERE IS A DISTINCT POSSIBILITY THAT THE HIGH SHEAR WILL OFFSET THE 
POLEWARD OUTFLOW AND CAUSE AN EARLY DISSIPATION OVER WATER. DYNAMIC 
GUIDANCE IS IN A LOOSE AGREEMENT WITH THE NORTHWESTWARD TRACK; 
HOWEVER, THERE IS A LARGE DISCREPANCY IN THE FORWARD TRANSLATION 
SPEEDS. THE JTWC FORECAST TRACK IS LAID CLOSE TO THE MULTI-MODEL 
CONSENSUS WITH LOW CONFIDENCE.  //
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